<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1,maximum-scale=1,user-scale">
    <title>栅格系统</title>
    <link rel="stylesheet" href="css/bootstrap.min.css"/>
    <script src="js/jquery.min.js"></script>
    <script src="js/bootstrap.min.js"></script>
    <style>
        .a{
            height: 50px;
            border:1px solid #ccc;
            background: #eee;
        }
    </style>
</head>
<body>
<div class="container a">
    <div class="row">
        <div class="col-md-6 a">1</div>
        <div class="col-md-6 a">1</div>
    </div>
    <div class="row">
        ...
    </div>
</div>


</body>
</html>